Honestly I think this is one of the reasons toribash died much faster than it should've. A large majority of players played for simply being being #1 or being ranked in a mod, it was an excellent fun factor.

It's also a good opportunity to flash around the newer ranking system while bringing back something that people loved. Perhaps order it like so: Rank Tier #, Mod Rank: ###

I don't think it should be integrated into current ranking, in my opinion it would be way more fun if we could simply have non-resetting mod ranks that didn't offer any rewards. It could be available only in public rooms so it would still be competitive to people that care about it.

Support, it was my main reason for playing back in the day, it made fighting so much fun, and much more interesting. In fact I used to be a high modrank and I'll fully admit I wouldn't have played half as much as I did if I wasn't focused on the grind to become top 10. It was always nice to (while it was flawed) see a visual indicator of your progress in a way.